MBB vs ESI

[Mister Mxyzptlk]

Feel free to post your thoughts, and I will be happy to respond, but I feel no need to prove my ability to critically read literature.

I will assume that you think the paper is valid since you cited it as evidence to support your views. Anyone who actually read this paper should know it didn't prove a damned thing.

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[ampaphb]

I will assume that you think the paper is valid since you cited it as evidence to support your views. Anyone who actually read this paper should know it didn't prove a damned thing.

Care to cite your specific concerns?

 

[Mister Mxyzptlk]

Given that the ISIS Guidelines do NOT recommend sensory stim, I hate to break it to you, but in this instance, you are not an iconoclast - you are just in with the rest of we mere mortals

I hate to break it to you, but I do sensory stim.

Getting back to the original question (and this is for everybody, not just amp) I am curious at what point someone is famous enough to disregard guidelines without any literature to back them up. How can we recognize a guru who has that level of entitlement? Are the criteria published somewhere?

 

[Mister Mxyzptlk]

Care to cite your specific concerns?

I sent an 11-point critique to two of the authors. When I get the responses I will post my original questions along with the responses if the authors allow it.

Here is a sneak preview: 45% of the patients in this study DID NOT receive MBBs.

 

[ampaphb]

I don't know about everyone else, but I would bet we all do something differently than the literature says - I personally just make damn sure I tell the patient that before going forward. For me, most of my indefensible procedures are at the point where there is little else to offer the patient other than significantly more invasive options.

 

[ampaphb]

I sent an 11-point critique to two of the authors. When I get the responses I will post my original questions along with the responses if the authors allow it.

Here is a sneak preview: 45% of the patients in this study DID NOT receive MBBs.

Just to elaborate on the veiled reference above,

"During the screening phase using blocks with ligno-Caine, 70 patients (39.8%) underwent medial branch blocks, 79 (44.9%) had intra-articular blocks" and 27 (15.3%) underwent both.
​

Apparently Dr. G does not accept intra-articular blocks as the equivalent of MBBs for diagnostic purposes. Stay tuned!

 

[Mister Mxyzptlk]

No, I do not, and I am surprised anyone would. They don't test the same thing.

 

[Pain_doc]

I don't accept facet joint injections either. My plan is to lesion a specific nerve, so the diagnostic test as a prelude should target that specific nerve. If the facet joint capsule is not intact, who knows what other structures are being anesthetized with the local.

 

[Mister Mxyzptlk]

Ok, I have heard back from one of the authors and am waiting for permission to reproduce his response. In the meantime get a copy of the article and see what you think of these points. If you don't have a copy email me and I'll copy it to you.

1. This was not a test of MBBs. It was a test of a mixed bag of MBBs and IA injections.

2. There were actually more IA injections than MBBs, and 15% had both. What does "both" mean? They had IA and MBB at the same time, or they had MBB for one block and IA for another?

3. All patients had lido blocks first and then bup blocks. If the lido was negative bup was not pursued. Why? You might have found that negative bup still had positive lido. Maybe bup sucks as a MBB test drug.

4. The lido blocks were performed along with other procedures but the bup blocks were not.

5. The article states that the lido blocks were done at the point of maximum tenderness and if there was still pain they received blocks of the adjacent joints. However, the repeat blocks were performed "at the segmental level at which the greatest relief had been obtained following the previous injection of lignocaine". This leads me to believe that the bup procedure was performed differently from the lido procedure, and that possibly fewer levels were anesthetized in the bup procedure.

6. For bup, "Ratings were performed at 30 min, 1 hr . . .". By whom? The patient? How about after the lido blocks? It would appear that the lido patients were evaluated on the table and the bup patients postop.

7. There was no breakdown of IA vs MBB success/failure. This is a major flaw. I want to know if most of the failures were in the IA group or the MBB group.

8. There is a discriminatory assumption that bup blocks are valid but lido blocks are not. The response to bup was considered the "criterion standard". I see no scientific basis for this assumption.

9. If the lido was positive and the bup was negative, it was assumed that the lido was a false-positive but there appears to be no entertainment of the notion that the bup was a false-negative.

10. 50% relief seems to be a generous cut-off value, especially when the criterion you set for RF success is 80%. I consider 50% relief a negative test. This may have generated a lot of false-positive lido blocks.

11. As mentioned in the article, perhaps some of the 50% responders had other pain generators. Since many people get relief for several weeks after MBBs, it is possible that they returned for the repeat procedure with the z-joint pain still under control, but the other pain generators (e.g., SI joints) were not relieved by the MBBs, thus creating a false-positive.

 

[Mister Mxyzptlk]

I have a reply from Nik Bogduk. He has asked me to summarize his remarks instead of a direct quote.

He agrees with what I've said in these 11 criticisms.

He had two main points to make. The first is to ask that this paper be judged in its proper historical perspective. There are certain things that he believed back then that he doesn't believe now. The specialty was young, there was little research, and no guidelines for practice or research.

In this instance, the investigators disagreed as to how to perform facet blocks, each having their own way. Some did MBBs, some did IAs, some did both, and each did it his own way for the study. Assumptions were made that probably would not have been made today, and the experimental design would certainly have been cleaner. As Nik says in his email, "This was as good as it got, in those days."

Certainly no one today would dream of doing MBBs at the same time as discography or ESI as part of a research endeavor. Hopefully, no one would do it as part of clinical treatment. One would also expect that the second set of blocks would be conducted the same way as the first set, and that all patients would receive the same kind of block.

The second set of comments has to do with a topic that he and I have been kicking around back and forth by email - how to validate MBBS. To quote again, "It is the sort of discussion that people do not have, and one that we did not have in 1994, because we knew nothing. We are wiser now, and can have these discussions."

One set of experiments that Nik suggested is as follows:

"What is needed for the lumbar spine is a study in which

Patients are allocated to receive either L or B
The controls involve a second and third block with the opposite agent randomized against placebo.

This gives us

The prevalence
The validation against placebo
A check of false responses to each of L and B."

As previously stated, my position is that comparative MBBs do just that - they compare two sets of MBBs. We are not interested in whether MBBs agree with each other. The more relevant question is "How well do MBBs predict successful RF?"

That is what our patients and the insurance companies want to know.

This requires a different type of experiment. In discussions a few days ago, we agreed on the following:

1. Do comparative blocks.
2. No matter what the outcome, do RF on everybody.
3. Sort it all out: How well do negative blocks predict negative outcomes? How well do positive blocks predict positive outcomes? Do you need double blocks or does a single block have sufficient predictive power?

Until we have that it's all heat and no light.

 

[PMR 4 MSK]

I've got an analogy here. I periodically do a series of lidocaine injections into prosthetic joints, such as shoulders or hips, for our orthopedic surgeons. They typically want 3 injections done a week apart and want to know what % of pain relief the patient gets, in order to decide wether to revise a painful prosthetic joint. This is apparently based on a protocol from Mayo. Like today, a guy I injected had 90% pain relief right after the injection, so we're going to do a repeat next week and another the week after.

The problem is what to do when they get different responses. Last month, I had a lady get 10% improvement on the first one, 50% on the second and 90 % on the third. Luckily, I don't have to be the one to make the decision as to which injection to hang your hat on. So that's 3 injections and they don't always agree.

 

[spondy14]

I've got an analogy here. I periodically do a series of lidocaine injections into prosthetic joints, such as shoulders or hips, for our orthopedic surgeons. They typically want 3 injections done a week apart and want to know what % of pain relief the patient gets, in order to decide wether to revise a painful prosthetic joint. This is apparently based on a protocol from Mayo. Like today, a guy I injected had 90% pain relief right after the injection, so we're going to do a repeat next week and another the week after.

The problem is what to do when they get different responses. Last month, I had a lady get 10% improvement on the first one, 50% on the second and 90 % on the third. Luckily, I don't have to be the one to make the decision as to which injection to hang your hat on. So that's 3 injections and they don't always agree.

Just curious, are you doing all of those under fluoro, or just some of them?

 

[PMR 4 MSK]

Just curious, are you doing all of those under fluoro, or just some of them?

All of them.

 

[Mister Mxyzptlk]

This is something that needs to be addressed because there is a definite bias towards the response to block being diagnostic. It makes good intuitive sense, and I use this approach in my practice. If you inject local into where the patient says there is pain and the pain goes away, you have found the pain generator.

What PMR 4 MSK is reporting contradicts this concept, and it's also something I see from time to time with ESIs. The first one is 90%, the second one is a flop, the third one is great, or it could go in any order, mediocre response #1 then 100% #2.

Are these serial joint injections being done with the same meds each time? In the patients with inconsistent responses are they perhaps coming in with different pain levels? Maybe when you numb them up the first time they get some improved ROM and at each successive injection it gets better. Do they ever go in reverse?

This is why you should only do one diagnostic block - the man with one watch always knows what time it is. The man with two watches is never sure. The man with three watches gets referrals from orthos who follow the Mayo clinic protocol.

 

[ampaphb]

This is why you should only do one diagnostic block

In your correspondence with Dr. Bogduk, did you ask him whether he does one or two diagnostic blocks before proceeding to RF?

 

[Mister Mxyzptlk]

In your correspondence with Dr. Bogduk, did you ask him whether he does one or two diagnostic blocks before proceeding to RF?

It was not in his initial reply, but we have a running dialog on this and related issues. In a recent email he expressed a very negative view of the efficacy of MBBs as a diagnostic/prognostic modality for lumbar pain. I did not ask him how many he does. IMHO if you consider something not worth doing you shouldn't be doing it at all.

Personally I don't agree with that. I think if properly done and properly evaluated they are very accurate.

We can have these ex-cathedra discussions forever and it will not get us any farther than where we are. Bogduk's opinions are valuable but ultimately they are just opinions, no matter how august the source is.

We have to generate data. I plan to take this up with Paul Dreyfuss next week since he is the person in charge of research for ISIS. It is my understanding that they have a 5-center study on RF and/or MBBs already in place but no one has enrolled a patient. I am going to take a look at their protocol and if I can live with it I'll try to enter patients into the study (assuming they will have me).

If not, I'll roll my own and see if they will help fund it. I just need someone to offset the costs of doing RFTC in someone with negative MBBs. If they have positive MBBs we can legitimately ask insurance to pay for it.

 

[ampaphb]

RF is one of the few procedures where there is reasonable support in the litterature for what we do. Gorback and I have proven in the past that we can argue re what shade of blue the sky is, but the truth is, there is far less litterature re ESI's, PDD, stims, and discography.

Given the limited time and resources our community has, I personally would put our research efforts towrds those procedures in need of documented indications and efficacy, rather than rehashing the minutia of how to work a patient up for RF.

 

[Tenesma]

ampa - you are kidding me right? did you see the NEJM article that dissed lumbar RFs???

 

[ampaphb]

ampa - you are kidding me right? did you see the NEJM article that dissed lumbar RFs???

I am not aware of any recent article in NEJM - could you post the reference?

 

[lobelsteve]

Cervical was in 1996:

Volume 335:1721-1726 December 5, 1996 Number 23


Percutaneous Radio-Frequency Neurotomy for Chronic Cervical Zygapophyseal-Joint Pain

Susan M. Lord, B.Med., Ph.D., Leslie Barnsley, B.Med., Ph.D., Barbara J. Wallis, B.Sc., Gregory J. McDonald, M.B., B.S., and Nikolai Bogduk, M.D., Ph.D.

ABSTRACT

Background Chronic pain in the cervical zygapophyseal joints is a common problem after whiplash injury, but treatment is difficult. Percutaneous radiofrequency neurotomy can relieve the pain by denaturing the nerves innervating the painful joint, but the efficacy of this treatment has not been established.

Methods In a randomized, double-blind trial, we compared percutaneous radio-frequency neurotomy in which multiple lesions were made and the temperature of the electrode making the lesions was raised to 80°C with a control treatment using an identical procedure except that the radio-frequency current was not turned on. We studied 24 patients (9 men and 15 women; mean age, 43 years) who had pain in one or more cervical zygapophyseal joints after an automobile accident (median duration of pain, 34 months). The source of their pain had been identified with the use of double-blind, placebo-controlled local anesthesia. Twelve patients received each treatment. The patients were followed by telephone interviews and clinic visits until they reported that their pain had returned to 50 percent of the preoperative level.

Results The median time that elapsed before the pain returned to at least 50 percent of the preoperative level was 263 days in the active-treatment group and 8 days in the control group (P = 0.04). At 27 weeks, seven patients in the active-treatment group and one patient in the control group were free of pain. Five patients in the active-treatment group had numbness in the territory of the treated nerves, but none considered it troubling.

Conclusions In patients with chronic cervical zygapophyseal-joint pain confirmed with double-blind, placebo-controlled local anesthesia, percutaneous radio-frequency neurotomy with multiple lesions of target nerves can provide lasting relief.

 

[lobelsteve]

Caragee also had an article, but not a study:

Volume 352:1891-1898 May 5, 2005 Number 18
Next



Persistent Low Back Pain

Eugene J. Carragee, M.D.

Since this article has no abstract, we have provided an extract of the first 100 words of the full text and any section headings.










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PubMed Citation




This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author's clinical recommendations.

A 49-year-old maintenance worker with a history of depression and previous reports of minor back pain is seen after four months of continuing low back pain. He has remained out of work for fear of worsening the injury. Magnetic resonance imaging (MRI) two weeks after the onset of pain showed only mild degenerative changes in the lumbar region without spinal stenosis or . . . [Full Text of this Article]

The Clinical Problem

Strategies and Evidence

Evaluation

Imaging

Other Diagnostic Techniques

Psychosocial Factors

Treatment

Pharmacologic Therapy

Nonpharmacologic Therapy

Injections and Neuroablation Procedures

Surgery

Areas of Uncertainty

Guidelines

Conclusions and Recommendations












No other relevant articles appeared in SEARCH: radiofrequency at NEJM.

 

[ampaphb]

The Carraggee review article, in relevant part, said:

In randomized trials, injections of glucocorticoids or anesthetic agents into the epidural space, lumbar disks, lumbar facets, and trigger points have not improved outcomes in patients who have chronic low back pain without radiculopathy, nor have injections of sclerosing agents into the lumbar fascia.
Radiofrequency ablation of the small nerves to the facet joints was ineffective in one randomized trial and showed a moderate effect (6 percent improvement in disability scores), which lasted only four weeks, in another. Although data are insufficient, some authors have suggested a possible benefit of neuroablation of the facet joint in the extremely small subgroup of patients with chronic low back pain who respond to placebo-controlled anesthetic blocks.

Percutaneous treatments directed at altering the internal mechanics or innervation of the disk by heat (intradiskal electrothermal treatment) or radiofrequency energy have been used, but data supporting their use are lacking. Recent randomized trials have shown either no effect or a benefit in only a small proportion of highly selected subjects.
​

 

[lobelsteve]

I have never met Carraggee, nor do I care to.

I believe he does discography in his center, but he publishes strongly against it.

In reviewing his articles, I get the feeling that he believes he alone can heal the pain, fix the spine, and make patients better. If I relied on Carraggee as a reading guide, I'd offer the patients only a referral to Californai for care.

 

[lobelsteve]

.

 

[Mister Mxyzptlk]

I know you feel strongly about it but once was enough.

I share your views of Carragee. IMHO, he is a hypocrite who says one thing and does another. I have heard that he has a hand in that new disk diagnostic procedure where you put in a catheter and infuse LA to diagnose discogenic pain. It wouldn't surprise me if that were true.

 

[Mister Mxyzptlk]

Rick Derby just replied to my email. I will not post the entire message, but here are selected quotes:

. . . all your points are well taken and all your questions are valid.

. . . it was the best there was at the time and it did provide a basis for emphasizing the role of diagnostic blocks.

The idea of being able to reliably and consistently provide longer relief with bupivicane versus lidocaine and derive useful diagnostic information from this information was and is dubious at best.

These are independent assessments by two of the study's authors and they are remarkably similar in tone and content.

In a scientific debate the source of an opinion is far less important than the content. Science is not the place to have hero worship and believe something just because a famous person said so.

It also pays to go back and look for yourself at where the dogma came from. Unfortunately, this is time consuming and we often rely on having the literature digested by someone, either in a lecture or in printed reviews, and we are at the mercy of their ability to interpret literature and their own personal biases.

As they say, don't believe anything you hear and only half of what you see. I'd make that 10% of what you read.

 

[ampaphb]

Rick Derby just replied to my email. I will not post the entire message, but here are selected quotes:

. . . all your points are well taken and all your questions are valid.

. . . it was the best there was at the time and it did provide a basis for emphasizing the role of diagnostic blocks.

The idea of being able to reliably and consistently provide longer relief with bupivicane versus lidocaine and derive useful diagnostic information from this information was and is dubious at best.

These are independent assessments by two of the study's authors and they are remarkably similar in tone and content.

In a scientific debate the source of an opinion is far less important than the content. Science is not the place to have hero worship and believe something just because a famous person said so.

It also pays to go back and look for yourself at where the dogma came from. Unfortunately, this is time consuming and we often rely on having the literature digested by someone, either in a lecture or in printed reviews, and we are at the mercy of their ability to interpret literature and their own personal biases.

As they say, don't believe anything you hear and only half of what you see. I'd make that 10% of what you read.

Derby's response does NOT say don't do double diagnostic blocks, however. So while we both agree that an article from 14 years ago would not be designed the same way today, neither Dr. Derby's NOR Dr., Bogduk's responses have supported the notion that a single diagnostic block is sufficient to proceed with RFA.

 

[Tenesma]

Volume 352:1891-1898 May 5, 2005 Number 18
Persistent Low Back Pain
Eugene J. Carragee, M.D.

this is where he disses RF...

and this ends up in the NEJM - it ain't helping

i agree about Carragee - he is a hypocritical nut case...

 

[Mister Mxyzptlk]

Derby's response does NOT say don't do double diagnostic blocks, however. So while we both agree that an article from 14 years ago would not be designed the same way today, neither Dr. Derby's NOR Dr., Bogduk's responses have supported the notion that a single diagnostic block is sufficient to proceed with RFA.

Neither thinks they are worth much at all.

I don't know how much more explicit Derby can be about whether double blocks provide meaningful information. He flat out says he doesn't think they provide useful information.

"The idea of being able to reliably and consistently provide longer relief with bupivicane versus lidocaine and derive useful diagnostic information from this information was and is dubious at best."

If you want to split hairs, fine. They did not say "don't do them", but that is not the question I asked. I asked the 11 questions cited above. They threw in these opinions themselves. You swallowed this paper whole. You were given ample opportunity to rebut any of my 11 points and failed to do so. Two of the authors admit unequivocally that the paper doesn't prove anything and that the 11 points are valid.

If you, as someone who admittedly does "indefensible procedures" want to do something that isn't worth doing it's your choice.

most of my indefensible procedures are at the point where there is little else to offer the patient other than significantly more invasive options.

 

[ampaphb]

Neither thinks they are worth much at all.

I don't know how much more explicit Derby can be about whether double blocks provide meaningful information. He flat out says he doesn't think they provide useful information.

"The idea of being able to reliably and consistently provide longer relief with bupivicane versus lidocaine and derive useful diagnostic information from this information was and is dubious at best."

If you want to split hairs, fine. They did not say "don't do them", but that is not the question I asked. I asked the 11 questions cited above. They threw in these opinions themselves. You swallowed this paper whole. You were given ample opportunity to rebut any of my 11 points and failed to do so. Two of the authors admit unequivocally that the paper doesn't prove anything and that the 11 points are valid.

If you, as someone who admittedly does "indefensible procedures" want to do something that isn't worth doing it's your choice.

What he said was that comparing lido to bupivicaine, and evaluating which lasts longer does not provide useful information. He makes no comment about double blocks vs single blocks.

 

[ampaphb]

If you, as someone who admittedly does "indefensible procedures" want to do something that isn't worth doing it's your choice.

Do you do PDD? it is indefensible. Do you do intradiscal steroids, GRC blocks, pulsed RF, or ESIs for axial back pain? Equally indefensible. Doesn't mean they don't have a reasonable hypothetical basis - merely that there is currently insufficent litterature to support performing them. Similarly, there is no justification in the litterature for doing single blocks and then going straight to RF. Works in your hands? Terrific!

 

[lobelsteve]

Do you do PDD? it is indefensible. Do you do intradiscal steroids, GRC blocks, pulsed RF, or ESIs for axial back pain? Equally indefensible. Doesn't mean they don't have a reasonable hypothetical basis - merely that there is currently insufficent litterature to support performing them. Similarly, there is no justification in the litterature for doing single blocks and then going straight to RF. Works in your hands? Terrific!

defensible vs indefensible

All of these procedures are defensible, operating at the wrong level is indefensible.

 

[Mister Mxyzptlk]

from Rick derby:

"Double blocks are not necessary – or to be polite – are an option. In addition, using the double block protocol adds to cost, morbidity, and patient dissatisfaction and may not increase the success rate (there is evidence to this point – recently in Pain Physician) ."


from ampaphb:

"Do you do PDD? it is indefensible. Do you do intradiscal steroids, GRC blocks, pulsed RF, or ESIs for axial back pain? Equally indefensible."

No, no, no, no, and no. Because, as you say, they are indefensible.

 

[radslooking]

this is quite comical...two diagnositic MBB's will actually cost more than the RF.......but why am i surprised....we are talking about insurance companies

I think its a little more complicated than that. The first MBB isn't factored in. The question is how many RFs will you prevent by doing a second (and potentially negative) MBB. Then you decide how many extra RF's will you save versus how many extra MBB's you've done.

Also, complications of each have to be taken into account as well. And do you repeat MBB's before repeating RF after it wears off? I assume not. If you don't then you to consider costs down the road of doing multiple RF's for an initial false positive MBB.

 

[Mister Mxyzptlk]

I think its a little more complicated than that. The first MBB isn't factored in. The question is how many RFs will you prevent by doing a second (and potentially negative) MBB. Then you decide how many extra RF's will you save versus how many extra MBB's you've done.

Also, complications of each have to be taken into account as well. And do you repeat MBB's before repeating RF after it wears off? I assume not. If you don't then you to consider costs down the road of doing multiple RF's for an initial false positive MBB.

Bogduk looked at this in 2000 and did some calculations based on fee schedules for both the US and Australia. He concluded that in most cases single blocks -> RF cost less than double blocks -> RF. In that article he opined that double blocks were necessary and he felt that the fact that economics dictated single blocks was a negative effect.

As I said before, in conversations since that time he has expressed doubts about the efficacy of lumbar medial branch blocks in general, and on that subject we continue to disagree. Rick Derby, as previously noted, thinks double blocks are a waste of time. And also as I said before, until the proper study is done, we can argue this forever and probably will.

I also heard from Paul Dreyfuss about the ISIS RF study and he confirmed that no patients had been enrolled. The inclusion criteria are very strict and apparently there was resistance from referring doctors so it seems to be dead in the water.

 

[Mister Mxyzptlk]

Those interested in the subject might also wish to look at Lord's paper from 1995 examining comparative blocks in cervical facets, vs placebo blocks.

"Comparative blocks were found to have a specificity of 88%, but only marginal sensitivity (54%). Although comparative blocks result in few false-positive diagnoses, their liability is that they result in a high proportion of false-negative diagnoses. Expanding the comparative blocks diagnostic criteria to include all patients with reproducible relief, irrespective of duration, increases sensitivity to 100% but lowers specificity to 65%."

Also there was a paper by Barnsley et al in 1993 where I found the truism that single blocks have a false positive rate of 27%.

Here are the results:

55 patients were lido (+)
2 of those were bup (-)
14 patients were bup (+) but the patient could not tell whether the duration of effect was longer with bup. They deemed those (-). I find this very questionable.

So what we have here is if the patient can't tell the 2nd block is longer they labeled it a false (+). If, on the other hand, you just look for reproducibility, then the false (+) rate is 2/55, or 4%, which is extremely accurate.

Once again, it pays to go back and look at where these things came from instead of quoting "gurus".

 

[Ligament]

I just had a patient:
MBB #1 with Lido 2%: >90% pain relief
MBB #2 with Marcaine .75%: <20% pain relief
MBB #3 with Marcain .5%: >90% pain relief

I did MBB #3 at his request and my curiosity.

 

[Tenesma]

hmmmm... at his request? do you think that may play a role in his report of relief?

i had one patient without any relief after RF - she then told me she had heard such great things about RF that she lied about her relief w/ MBB.... great... this is what the internet does to our field.

 

[lobelsteve]

So why don't we just skip all the blocks and do RF for suspected facetogenic related pain?

I can't see the downside at this point.

 

[Mister Mxyzptlk]

I just had a patient:
MBB #1 with Lido 2%: >90% pain relief
MBB #2 with Marcaine .75%: <20% pain relief
MBB #3 with Marcain .5%: >90% pain relief

I did MBB #3 at his request and my curiosity.

When do you evaluate them for response? Some people send the patient home and then ask at the next visit, others send them home with a diary for the next visit, and some do an immediate postop evaluation.

 

[ampaphb]

Those interested in the subject might also wish to look at Lord's paper from 1995 examining comparative blocks in cervical facets, vs placebo blocks.

"Comparative blocks were found to have a specificity of 88%, but only marginal sensitivity (54%). Although comparative blocks result in few false-positive diagnoses, their liability is that they result in a high proportion of false-negative diagnoses. Expanding the comparative blocks diagnostic criteria to include all patients with reproducible relief, irrespective of duration, increases sensitivity to 100% but lowers specificity to 65%."

Also there was a paper by Barnsley et al in 1993 where I found the truism that single blocks have a false positive rate of 27%.

Here are the results:

55 patients were lido (+)
2 of those were bup (-)
14 patients were bup (+) but the patient could not tell whether the duration of effect was longer with bup. They deemed those (-). I find this very questionable.

So what we have here is if the patient can't tell the 2nd block is longer they labeled it a false (+). If, on the other hand, you just look for reproducibility, then the false (+) rate is 2/55, or 4%, which is extremely accurate.

Once again, it pays to go back and look at where these things came from instead of quoting "gurus".

Maybe I am missing something, but doesn't that result in the take home message that what is typically done (two blocks, both have to provide X% relief, we don't care which lasted longer) yields a 4% false positive rate, which is "very accurate", especially when compared to the single block paper that reports 27% false positive rate? To me, that says that if you only do single blocks, you are going on to RF unnecessarily 23% of the time.

 

[Ligament]

When do you evaluate them for response? Some people send the patient home and then ask at the next visit, others send them home with a diary for the next visit, and some do an immediate postop evaluation.

Good question.

I do pre-op facet loading to localize the pain.
Post op facet loading to see if there was pain relief.
Post op pain log filled out every 15 minutes for 8 hours.

 

[Mister Mxyzptlk]

Maybe I am missing something, but doesn't that result in the take home message that what is typically done (two blocks, both have to provide X% relief, we don't care which lasted longer) yields a 4% false positive rate, which is "very accurate", especially when compared to the single block paper that reports 27% false positive rate? To me, that says that if you only do single blocks, you are going on to RF unnecessarily 23% of the time.

Yes, you are missing something.

 

[ampaphb]

Yes, you are missing something.

Care to elaborate?

Also, do you happen to have any peer-reviewed RCTs that document the efficacy the single block paradigm you apparently advocate?

 

[Mister Mxyzptlk]

Good question.

I do pre-op facet loading to localize the pain.
Post op facet loading to see if there was pain relief.
Post op pain log filled out every 15 minutes for 8 hours.

I do something similar. I usually mark the skin and then block whatever is underneath. Then I retest for tenderness on the table and see if there are other levels that need to be blocked. Then 15-20 minutes postop I evaluate them in the exam room or PACU. I don't trust diaries or patient recall. Quite often they will report persistent pain and if you don't examine them you might miss the fact that you have teased apart facet pain from SI pain.

I think this is why some studies turn out so badly. If you don't verify the results postop and rely on self-reporting then there will be some false-negatives due to co-existing pain generators in the vicinity.

I also disagree with papers that use >50% relief as the inclusion criterion. I think that leads to false-positives and poor results with RF. In my practice if it's not close to 100% (allowing for the co-existence of other painful areas) it's a failed test.

 

[Mister Mxyzptlk]

Care to elaborate?

Sure. You can find the explanation here: http://www.mathfoundation.com/

 

[PMR 4 MSK]

hmmmm... at his request? do you think that may play a role in his report of relief?

i had one patient without any relief after RF - she then told me she had heard such great things about RF that she lied about her relief w/ MBB.... great... this is what the internet does to our field.

I had a work comp pt recently tell me immediately post-op his pain was just about gone, then tell the nurse 2 minutes later when I wasn't around that his pain was doubled post-injection. He later admitted to wishful thinking.

 

[Tenesma]

gorback i think your technique is fine with purely posterior element pain - but when there are other factors in play (disc, spondy, muscle, fibro, yada-yada) I find the pushing on the back then injecting technique somewhat misleading...

i know there is no literature for this, but I go based on imaging first.... so if on MRI there appears to be obvious facet disease (ie: L3/L4 spondy w/ fluid in the facets that look big enough to eat a small child), that becomes the target of MBB - I get thin-slice CT scans in about 90% of my posterior element pain patients... it really helps me hone in on what the source of the pain is (as long as it matches up with where the patient complains of pain)...

i have them report pain relief within 15 minutes (right before departure) - then i give them three tasks to do at home (tasks that usually cause their pain: carrying laundry up the stairs, vacuuming, gardening, etc) and I then have them call me back after 4 hours - reporting % relief and their abilities to perform the 3 tasks that are usually difficult for them...

 

[Mister Mxyzptlk]

Actually there is literature on this and it says there is little correlation between what you see on imaging and whether it hurts. If you must use imaging your best best is probably either bone scan or T2 fat-saturation MRI.

 

[Tenesma]

i still can't get my Rads guys to do axial Fat Sats - and they rarely do sagittal fat sats...

i also have very crappy SPECT around me - it looks worse than a traditional bone scan...

what i do like about thin-slice CT scan is that it can reveal anatomic deformities that aren't evident on MRI or bone scan - ie: fragmentation of the facet joints or hypoplasia of the facet joints...